1. Field of the Invention
The invention relates to a cell sheet construct for neurovascular reconstruction, particularly to a cell sheet construct that is formed by co-culturing vascular endothelial cells with neural stem cells being physically in direct contact with each other to differentiate into branching vasculatures and neurons of the cell sheet construct.
2. Description of the Related Art
Cell-based therapies have been emerging as a promising therapeutic strategy for treating damaged or diseased organs and tissues. However, when being applied to the highly complicated nervous system, such as stroked brains, cell-based therapies remain to be improved further. In order to restore function of the damaged central nervous system by cell-based therapies, neurons have to be located in an appropriate microenvironment in the brain to transmit neural signals. Since neurons, which transmit neural signals, are regulated by vascular endothelial cells and interact with each other, neurons have to be situated in the neurovascular unit (NVU) to function appropriately.
Some researchers tried to create regenerated neurovascular tissue in vitro by the methods of tissue engineering. However, these teams were unable to create cell sheet having neurovascular tissues by co-culturing neural stem cells and vascular endothelial cells [Hicks C, Stevanato L, Stroemer R P, Tang E, Richardson S, Sinden J. In vivo and in vitro characterization of the angiogenic effect of CTX0E03 human neural stem cells. Cell transplantation. 2013; 22:1541-1552]. The main difficulty of these researches is that the suitable conditions for differentiation of neural stem cells and vascular endothelial cells are different. For example, Hicks et al. used Matrigel as the substrate for vascular endothelial cells to form branching vasculature tissues, but it was unable to provide neural stem cells an appropriate microenvironment to differentiate into neurons. In addition, because Matrigel is a mixture, Matrigel from different manufactures and different batches has different ingredients, which cannot provide a consistent condition to induce differentiation of neural stem cells.
Therefore, it is necessary to develop the techniques of constructing the neurovascular tissue, a cell sheet of neural stem cells-vascular endothelial cells (NSC-EC) having differentiated neurons and branching vasculatures, in order to promote neurovascular reconstruction.